Soft step top lift for shoes and method thereof

ABSTRACT

A soft top lift member for a shoe heel wherein the top lift member is made by mixing a filler carbon material with a thermoplastic elastomer to form a filled elastomer. The filled elastomer is then formed into a top lift member for a shoe heel by using an injection molding process. The top lift member is then attached to a shoe heel. The thermoplastic elastomer can be a relatively soft thermoplastic polyurethane material and the carbon material can be a carbon powder. The filler or carbon powder is provided to enhance abrasion resistance properties.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to U.S. Provisional Patent Applications Ser. No. 61/180,118, filed on May 20, 2009, entitled SOFT STEP TOP LIFT FOR SHOES AND METHOD THEREOF, which application is hereby incorporated by reference to the extent permitted by law.

BACKGROUND OF THE INVENTION

The present invention relates generally to a top lift member for a shoe heel and, more particularly, to a soft step top lift member for a shoe made by mixing carbon powder material in combination with various thermoplastic materials.

A shoe top lift assembly is the bottom-most part of a shoe's heel which comes into contact with the ground during walking. A top lift member can be used on a wide variety of shoes and includes a member having a bottom surface which comes into contact with the ground surface.

The top lift members typically wear out faster and then the shoes are either thrown away or taken to a shoe repair shop for replacement of the top lift members. For the comfort and safety of the wearer, the top lift member should exhibit good cushioning and non-slip characteristics. In other words, the top lift member should have good frictional performance; it should be resistant to abrasion and stress; and it should provide firm support to the user.

Thus, it would be desirable to provide an improved top lift member which has improved non-slip characteristics as compared to the prior art.

It would be also desirable to provide a top lift member for a shoe which provides enhanced anti-abrasion properties.

SUMMARY OF THE INVENTION

The present invention is directed to the use of carbon particles as a filler during the making of the shoe top lift member. The shoe includes an upper, a midsole and an outsole. The midsoles and outsoles typically comprise a combination of synthetic and natural rubber, thermoplastics and thermosetting or otherwise cured plastics, and leather materials. The outsole is secured to the upper or midsole such as by cementing and/or stitching and has a bottom surface portion with a heel region. The heel of a shoe is typically attached to the heel region of the outsole. The top lift member is the bottom-most part of the heel of a shoe, namely, that part of the heel which comes into contact with the ground.

In one aspect of the present invention, a method of making a shoe top lift member using carbon powder as a filler is disclosed. The carbon powder is added to an elastomer to form a filled elastomer. The filled elastomer is then formed into a top lift member for a shoe by using an injection molding process. The elastomer is generally a relatively soft thermoplastic polyurethane material which provides a superior coefficient of friction or slip resistance when injection molded to form the top lift member. The filler material of carbon powder is provided to enhance abrasion resistance properties. The top lift member, once formed, is then attached to the shoe heel.

In accordance with the present invention there is provided a process for forming a molded shoe top lift member comprising a carbon powder as a filler and a base material such as a thermoplastic elastomer. The amount of carbon added is about 5% by weight or in a range of about 2-5% by weight of the filled elastomer. The carbon is in powder form which has diameters ranging from about 2-4 microns. Generally, the carbon powder material and the base material are mixed under sufficient pressure and temperature for a sufficient residence time to at least partially plasticize some portion of the materials so as to form a moldable product. The plasticized moldable material may then be molded, for example, by injecting the plasticized material into a mold.

The top lift member comprised of a thermoplastic elastomer and carbon powder as a filler has better non-slip characteristics; it provides better abrasive resistance properties; and it yields improved physical characteristics over previous top lift members.

Specific advantages and features of the present top lift member will be apparent from the accompanying drawings and the description of several illustrative embodiments of the present invention.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of one embodiment of a shoe using a top lift member constructed in accordance with the teachings of the present invention.

FIG. 2 is an enlarged fragmentary bottom view of the top lift member of FIG. 1.

FIG. 3 is a fragmentary perspective view of the top lift member and heel of FIG. 1.

It should be understood that the drawings are not necessarily to scale and that the embodiments disclosed herein are sometimes illustrated by fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted. It should also be understood that the invention is not necessarily limited to the particular embodiments illustrated herein. Like numbers utilized throughout the various figures designate like or similar parts or structure.

DETAILED DESCRIPTION

As illustrated in FIGS. 1-3, the present invention provides a shoe 1 having a top lift member 10 attached to a shoe heel 12. The shoe 1 generally comprises a shoe upper and a sole assembly attached to the shoe upper. The sole assembly generally includes an insole, a midsole and an outsole having three sections, namely, a forefoot section, a midsection and a heel 12 which is attached to the sole at its heel seat. The heel 12 includes a rigid heel block 14 and a top lift member 10 located therebeneath.

The top lift member 10 of the present invention includes a base 16 having a top surface (not shown), a bottom surface 18 and a peripheral side wall 20. The top lift member 10, like the forefoot of the sole, contacts the surface over which the wearer walks. In one embodiment, the base 16 includes outer stability ridges 22 disposed on the bottom surface 18 to enhance traction and stability. The peripheral side wall 20 conforms to the exterior surface of the heel block 14 and the top surface (not shown) of the top lift member 10 is attached with a suitable attaching means to the bottom portion of the heel block 14 such that the peripheral side wall 20 lies substantially flush with the exterior surface of the heel block 14. The base 16 is formed from a material that is more rigid and is reasonably resistant to wear, inasmuch as it comes into constant contact with the surface over which the wearer walks, yet possesses a measure of flexibility for comfort. Such materials are well known in the art of shoe top lift members and can include, but are not limited to, elastomers such as a thermoplastic polyurethane. The term elastomer in this application is used loosely to include various macro-molecular materials, natural or synthetic, which have rubber-like properties and are used for shoe bottoms. In a preferred embodiment, synthetic materials can be used as this part of the shoe is subject to maximum wear. The thickness or height of the top lift 10 member is generally about 9-10 millimeters. However, the height of the top lift member can vary to conform to the use and shape of the shoe.

In one aspect of the present invention, the composition of the present top lift member 10 includes a base material of thermoplastic elastomer and an abrasion resistant filler material of carbon particles. The carbon particles are mixed with the thermoplastic elastomer such as a softer thermoplastic polyurethane during the process of injection molding. The ratio of the carbon particles to the base material may vary over a wide range depending upon the ultimate characteristics desired in the top lift member and the resulting shoe product. In a preferred embodiment, the amount of carbon particles added is about 5% by weight or in a range of about 2-5% by weight of the filled elastomer. The carbon is in powder form with each particle having a diameter ranging from about 2-4 microns. This patent application uses the term “filler” to include carbon both as a particulate and as a powdered friction material. Other materials can be added to the elastomer or elastomer/filler mixture as well.

In the case of a thermoplastic elastomer, the process for forming the top lift member of the present invention may include the steps of mixing the carbon powder with the thermoplastic elastomer in a suitable mixer to form a uniformly distributed mixture. A suitable elastomer is typically provided in bulk. It is then mixed in a suitable mixer with the carbon powder. The filler material is added to the elastomer material prior to its being formed into a top lift member to form the filled elastomer material. In one embodiment, the mixed material is milled or extruded by a roller mill or an extruder to process the mixed materials and to form the mixed material into a desired form. The mixture of elastomer and filler can be extruded into rods or ribbons and then cut into pellet form. The mixture could also be added in bulk to an extruder. The formed pellets can be added to the hopper of the extruder as a feed material. The filled elastomer material can then be heated in the extruder to a flowable temperature and injected, as is well known in the art, into a mold cavity to form the top lift member. An injection mold is typically cooled or maintained at a temperature below the melting temperature of the thermoplastic elastomer, allowing the top lift member to set or solidify in its as-molded form, removed from the mold and then processed into finished shoes by securing the molded top lift member to a heel.

It is also recognized that the filled elastomer material can be processed using a wide variety of different molding processes other than injection molding such as compression molding, transfer molding, extruding, or any other suitable method for fabricating the top lift member 10.

Thus, there has been shown and described several embodiments of a novel top lift member. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present invention will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow. 

1. A molded shoe top lift member comprising: a base material including a thermoplastic elastomer; and a filler of carbon material mixed in the base material to form a substantially uniformly distributed filled elastomer.
 2. The molded shoe top lift member of claim 1 wherein said carbon material is present in the range of between about 2% and about 5% by weight of the base and filler material.
 3. The molded shoe top lift member of claim 1 wherein the carbon material is in the form of a powder.
 4. The molded shoe top lift of claim 1 wherein the particle size of the carbon material is about 2-4 microns.
 5. A method for making a shoe top lift member comprising the steps of: providing carbon particles; mixing the carbon particles and a base material in predetermined quantities to form a substantially uniformly distributed filled elastomer; and forming the thus filled elastomer into a top lift member.
 6. The method of claim 5 wherein the carbon particles comprise about 5% by weight of the filled elastomer.
 7. The method of claim 5 wherein the carbon particles are in powder form.
 8. The method of claim 5 wherein the size of the carbon particles is in the range of about 2 microns to about 4 microns. 